As compared to silicon (Si), silicon carbide (SiC) has excellent physical properties; it has three times as large as a band gap, about 10 times as large as a breakdown field strength, and about three times as large as a heat conductivity. By utilizing those properties, it is possible to realize a low-loss semiconductor device excellent in high-temperature performance.
Such semiconductor devices utilizing those SiC properties may include metal oxide semiconductor field effect transistors (MOSFETs) and insulated gate bipolar transistors (IGBTs). Among those device structures, a gate-electrode having a trench-type structure has merits for finer patterning and higher integration densities than the planar type, being expected to further lower the turn-on resistance.
The properties of the gate insulating film provide one of the main important factors that determine the performance and reliabilities of the semiconductor devices. Especially in the trench type semiconductor device, a high electric field is applied to an insulating film on the bottom portion of the trench, it is important to maintain its reliabilities. The properties of the gate insulating film formed on the side surface of the trench have a great influence on power driving force of the semiconductor device.